1. Field of the Invention
The present invention relates to an ingot support device a slicing apparatus which is used to slice out a thin wafer from the end face of a cylindrical ingot in a semiconductor wafer manufacturing process.
2. Description of the Related Art
In a slicing apparatus, the upper end of a cylindrical ingot is held by a hold mechanism provided in the slicing apparatus by use of an adhesive or the like and, while the lower end portion of the ingot is being pressed against the internal peripheral edge of a blade revolving at high speeds, the ingot lower end portion is sliced out into a thin disc-shaped wafer by the internal peripheral edge blade. In the above-mentioned slicing apparatus, the ingot that is held in a cantilevered manner by the hold mechanism suffers a slicing resistance, that is, the upper end portion of the ingot that is held by the hold mechanism is given a flexing pressure, so that the ingot is caused to move back in a direction away from the above-mentioned blade edge. The flexing pressure is small at the beginning of slicing, gets gradually larger as the slicing advances, and gets small again in the neighborhood of the end of the slicing. Therefore, there is a problem that the sliced surface of the wafer may not be a flat surface but be a curved one. In order to solve this problem, there has been proposed a technique to hold the lower end portion of the ingot, namely, the portion thereof disposed close to the blade edge in a fixed manner. For example, this technique is disclosed in Japanese Utility Model Publication No. 54-1961, No. 50-1310 and the like. In the former model, in the inner tip end of a cylindrical holder there is provided a structure which is capable of vacuum adsorption of an ingot so as to fix and hold the end portion of the ingot. In the latter, there is provided a structure to further press the ingot end portion, which is located along a holding table, toward the holding table so as to fix and hold the ingot end portion. In either of these structures, however, since the ingot is fixed and held by applying partial loads thereto, the hold surface of the ingot upper end is also affected by the loads, as in the above-mentioned slicing resistance, so that a pressure is given to the ingot to peel off the adhesive surface thereof. Therefore, in order to avoid the above-mentioned drawbacks, the ingot must be set with high accuracy, resulting in the more troublesome and complicated setting operation.